Popemania may have moved on to the afterlife, but our memories of it endure: the wide-eyed references to Francis as a “rockstar,” the jet-black Fiat, and yes, even the Popemojis. Papal pomp aside, perhaps the most memorable moment of the visit was the Pope’s address to a joint session of Congress, in which he spoke pointedly about climate change, the arms trade, and the death penalty, among other issues.

In an effort to summon the better angels of our nature as well as the ones hovering idly atop a gridlocked Washington D.C., Francis structured the speech around the legacies and lessons of four influential Americans: Abraham Lincoln, Martin Luther King Jr., Dorothy Day, and Thomas Merton. Many understood his choice of the first three—a revered president, a civil rights leader, and a Catholic social justice icon—but expressed befuddlement at the last: a Trappist monk who spent the bulk of his adult life at an abbey in rural Kentucky.

In his speech, Francis explained his selection this way: “Merton was above all a man of prayer, a thinker who challenged the certitudes of his time and opened new horizons for souls and for the Church. He was also a man of dialogue, a promoter of peace between peoples and religions.”

This description of Merton—as a contemplative within and a bridge-builder without—may not have resonated much with America’s political heavyweights. But it’s safe to say that the Pope was aiming his words not at our politicians in particular, but to Buddhists and other spiritual practitioners all over the world. Through his willingness to engage publicly with prominent Buddhist teachers like D. T. Suzuki and Thich Nhat Hanh, Merton became instrumental in popularizing Buddhism in the West, especially Zen. He set aside personal and parochial bias in order to elevate a religious tradition that he respected as much as his own. For that reason, Francis could not have selected anyone better to, as he put it, “inspire [us], even amid conflicts, and in the here and now of each day, to draw upon our deepest cultural reserves.”

Born in France and raised Anglican, Merton first came across Eastern spirituality in 1937 at the age of 22, when he read Aldous Huxley’s Ends and Means, a philosophical treatise that extols the mystical insight derived from an ascetic lifestyle. Then a student at Columbia University, Merton soon sought out the guidance of a Hindu monk named Mahanambrata Bramachari who, unexpectedly enough, advised the young student to read the mystical literature within Merton’s own tradition. That path led Merton to convert to Catholicism in 1939 and take residence at the Abbey of Gethsemani in New Haven, Kentucky two years later.

His interest in Eastern spiritual traditions, however, remained. Merton struck up a friendship with Zen teacher and scholar D. T. Suzuki, which culminated in the publishing of a joint book entitled Zen and the Birds of Appetite (1968). Other interfaith books by Merton, like The Way of Chuang Tzu (1965)and Mystics and Zen Masters (1967), proved crucial in bringing Buddhism to a wider audience during a time when Westerners, especially young ones, were particularly receptive.

An ardent critic of the Vietnam War, Merton also became fast friends with the Vietnamese monk Thich Nhat Hanh, who himself garnered international attention for advocating that both sides pursue peace. In 1966, while on a tour of the United States to build opposition to the war, Thich Nhat Hanh stopped at Gethsemani Abbey to speak with Merton. It was the first and only time they met. Shortly after the meeting, at a time when Vietnamese government officials were threatening to block the Buddhist monk’s safe return home, Merton published an essay entitled “Nhat Hanh Is My Brother,” which emphasized how the points of commonality between the two religious figures were indicative of a broader international coalition for peace:

I have said Nhat Hanh is my brother, and it is true. We are both monks, and we have lived the monastic life about the same number of years. We are both poets, both existentialists. I have far more in common with Nhat Hanh than I have with many Americans, and I do not hesitate to say it. It is vitally important that such bonds be admitted. They are the bonds of a new solidarity and a new brotherhood which is beginning to be evident on all the five continents and which cuts across all political, religious and cultural lines to unite young men and women in every country in something that is more concrete than an ideal and more alive than a program.

Having read and written about the overlap between Catholicism and Buddhism for many years, Merton developed an overwhelming desire to travel to Asia. In 1968, the Abbey granted him permission to do so. On his travels, he met the Tibetan Buddhist teacher Chögyam Trungpa Rinpoche, whom he described as a “completely marvelous person . . . without front or artifice, deep, awake, wise.”

On the same trip, Merton visited with His Holiness the Dalai Lama, an interaction that Tricycle explored in an interview with Harold Talbott, a fellow Catholic convert who was studying with the Dalai Lama at the time and witnessed the exchange. Talbott described the conversation:

It was about how you live the contemplative life in the West and what you do to make it possible in this modern world to live the life of a monk in the West. How do you stave off spiritual annihilation? These conversations were very much Merton equipping himself with the transmission of Buddhism from the Dalai Lama and very much the Dalai Lama equipping himself with the low-down from a reliable guide.

Though he spent most of his life discussing Zen Buddhism in particular, Merton used the trip as an opportunity to gain understanding of other traditions. Unfortunately Merton’s wider relationship to Buddhism would not deepen, as he died only weeks later in an accident in his hotel room in Bangkok, Thailand. It occurred 27 years to the day after his entrance into Abbey of Gethsemani. He was 53 years old.

Toward the end of his speech, Pope Francis credited Merton for his “capacity for dialogue and openness to God.” The two traits are both exemplified in a famous passage from Zen and the Birds of Appetite:

Both Christianity and Buddhism show that suffering remains inexplicable, most of all for the man who attempts to explain it in order to evade it, or who thinks explanation itself is an escape. Suffering is not a ‘ problem’ as if it were something we could stand outside of and control. Suffering, as both Christianity and Buddhism see, each in its own way, is part of our very ego-identity and empirical existence, and the only thing to do about it is to plunge right into the middle of contradiction and confusion in order to be transformed by what Zen calls ‘the great death’ and Christianity calls ‘ dying and rising with Christ.’

Merton’s work continues at the Thomas Merton Center, an organization in Pittsburgh, PA that advocates on issues ranging from fossil fuel divestment to ending drone warfare.